>This is an unrelated point, is your contention that the US is better off with unserious students?

It's that America has the capacity to fully absorb it's talent so it's not a problem. The reason why other countries have more is because they don't have the capacity to absorb them due to less opportunities so the competition is higher. Many of those "serious" students in China or India will still end working in factory jobs and delivery drivers because they weren't good enough.

>It's a big reason those students immigrant to the US and companies here hire those people in masses

Eh, if they were hiring domestic students I wouldn't say there would be much of difference. Unless if you are running a startup, most of these "serious" students will be just writing basic CRUD apps. Value comes from experience here, not talent. Well, if I was American though, I wouldn't bother competing againt millions of desperate Chinese or Indians for opportunity cost anyways, I'd be going more into law or finance. And those fields are less diverse.